After you've read the ingredients on the label, check out how much saturated fat and sugar is in your food. Dr. Roizen says you want to buy foods that contain less than four grams of saturated fat and less than four grams of sugar per serving.
Keep in mind—polyunsaturated and monounsaturated fats are good for you and help fight depression.
Can't seem to find any food that fits the bill? Dr. Oz says you should head over to the produce aisle and stock up on fresh fruits and vegetables. Packaged goods usually contain harmful, artificial ingredients because they're designed to stay on the shelf for years, he says.